Gamma Knife radiosurgery combined with stereotactic aspiration as an effective treatment method for large cystic brain metastases

Abstract

In the present study, the efficacy and clinical outcomes of stereotactic aspiration combined with the Gamma Knife radiosurgery (GKRS) method were evaluated retrospectively for patients with large cystic brain metastases. This combined method aims to decrease the tumor weight (volume) and increase the possible radiation dose. The present study involved 48 patients who were diagnosed with cystic metastatic brain tumors between January 2008 and December 2012 in the Department of Neurosurgery of Nanfang Hospital Southern Medical University (Guangzhou, China). Every patient underwent Leksell stereotactic frame, 1.5T magnetic resonance imaging (MRI)-guided stereotactic cyst aspiration and Leksell GKRS. Subsequent to the therapy, MRI was performed every 3 months. The results indicated that 48 cases were followed up for 24-72 months, with a mean follow-up duration of 36.2 months. Following treatment, 44 patients (91.7%) exhibited tumor control and 4 patients (8.3%) experienced progression of the local tumor. During this period, 35 patients (72.9%) succumbed, but only 2 (4.2%) of these succumbed to the brain metastases. The total local control rate was 91.7% and the median overall survival time of all patients was 19.5 months. The 1-year overall survival rate was 70.8% and the 2-year overall survival rate was 26.2%. In conclusion, these results indicated that the method of stereotactic cyst aspiration combined with GKRS was safe and effective for patients with large cystic brain metastases. This method is effective for patients whose condition is too weak for general anesthesia and in whom the tumors are positioned at eloquent areas. This method enables patients to avoid a craniotomy, and provides a good tumor control rate, survival time and quality of life.

Keywords: Gamma Knife radiosurgery; colloidal phosphorus-32; cystic brain metastases; stereotactic cyst aspiration.

Figure 1.

T1-weighted (axial contrast-enhanced) magnetic resonance imaging of a 24-year-old woman diagnosed with a large cystic brain metastasis. The prescribed dose for the Gamma Knife radiosurgery (GKRS) was 16 Gy, with 0.5 mci colloidal phosphorus-32 radiation therapy. (A) Prior to aspiration. (B) Subsequent to aspiration at 3 months post-GKRS.

Figure 2.

T1-weighted (axial contrast-enhanced) magnetic resonance imaging of a 45-year-old man diagnosed with a large cystic brain metastasis. The prescribed dose of Gamma Knife radiosurgery (GKRS) was 18 Gy. (A) Prior to aspiration. (B) Subsequent to aspiration at 3 months post-GKRS.

Figure 3.

Kaplan-Meier plot showing the overall survival rate of the patients.